BRPI1016146B1 - communication device, method and system, and computer-readable storage medium - Google Patents

Abstract

APPLIANCE, METHOD AND COMMUNICATION SYSTEM, AND, COMPUTER PROGRAM Even if the lengths of data to be transmitted to the respective users from a plurality of users are different, the frames as concurrently multiplexed are eventually transmitted with the same frame length, even if the frame lengths for the respective users of a plurality of users are different when transmission requests are received from a higher-level layer, a communication device aggregates two or more short frames to reconstruct longer frames, and the communication device eventually transmits the frames as multiplexed concurrently with the same frame length. On the transmission side, the transmission power, which can be used for each of a plurality of destination communication stations, is increased because of the reduction in the total number of frames to be multiplexed, while on the receiving side, the instability of the operation AGC can be eliminated.

Description

Technical field

[001] The present invention relates to a communication device, a communication method, a computer program, and a communication system that employs Space Division Multiple Access (SDMA) in which a plurality of users share wireless resources on a spatial axis and, in particular, to a communication device, a communication method, a computer program, and a communication system that multiplexes frames having a frame format of varying length and intended for a plurality of users and transmits the paintings.

Fundamentals of Technique

[002] Wireless communication was developed and used as a communication technique to eliminate the wiring operation required in existing wired communication and still carry out communication from mobile terminals. For example, an example of the standard for a wireless LAN (Local Area Network) is IEEE (The Institute of Electrical and Electronic Engineering) 802.11. IEEE 802.11a / g has already been widely disseminated

[003] The IEEE 802.11a / g standard supports a modulation method that achieves a maximum communication speed (the physical layer data rate) of 54 Mbps using Orthogonal Frequency Division Multiplexing (OFDM) in the 2 band, 4 GHz or in the 5 Ghz band. In addition, in the 802.11n standard, which is an extension of the IEEE 802.11a / g standard, a higher bit rate is achieved using the MIMO (Multiple Input - Multiple Output) communication scheme. The MIMO communication scheme is a communication scheme (an existing communication scheme) that performs a spatially multiplexed sequence using a transmitter and a receiver, each including a plurality of antennas. IEEE 802.11n can provide a high transmission capacity that is greater than 100 Mbps. However, with an increase in the amount of information in the transmitted content, a higher bit rate is required.

[004] For example, by increasing the number of antennas of the MIMO communication devices and increasing the number of spatially multiplexed sequences, the transmission capacity of pier-to-pier communication can be increased while maintaining compatibility in the downward direction. However, in the future, the communication transmission capacity between a plurality of users needs to be increased in addition to increase the transmission capacity per user in the communication.

[005] The IEEE 802.11ac working group tries to establish a wireless LAN standard that uses the frequency band lower than or equal to 6 GHz and that performs a data transmission speed that is greater than 1 Gbps. In order to achieve such a wireless LAN standard, a space division multiple access scheme in which a plurality of users share wireless resources on the space axis, such as multiple MIMO (MU-MIMO) or SDMA (Access user) Multiple by Space Division), is a promising scheme.

[006] Currently, space division multiple access is developed as one of the basic technologies for a next generation cell phone system based on Time Division Multiple Access (TDMA), such as PHS (Handheld Telephone System) Personnel) or LTE (Long Term Evolution). In addition, in the technical field of wireless LAN, one-to-many communication gains much more attention, as described above. However, few applications are available in this field. One reason for this is that it is difficult to efficiently multiplex a plurality of users in packet communication.

[007] Note that a communication system was developed using an RTS package, a CTS package, and an ACK package that have a package format having downward compatibility with IEEE 802.11 and combining the following two techniques: carrier sensing of the existing IEEE 802.11 standard and multiple access by space division using an adaptive array antenna (refer to, for example, PTL 1).

[008] When the space division multiple access scheme is applied to a wireless LAN, a frame of varying length can be multiplexed on the same time axis. At that time, if the lengths of data items transmitted to all of a plurality of users are the same, no problem arises. However, if the lengths of all the frames to be multiplexed are not the same due to the difference between the transmitted data lengths, the level of frame multiplexing during a transmission interval is decreased or increased and, therefore, the total power of transmission is abruptly changed. If frames having different lengths are directly multiplexed if transmitted, the received power is abruptly changed on the receiver side due to an increase or decrease in the level of frame multiplexing. Therefore, an unstable operation occurs in terms of automatic gain control (AGC). In this way, a variety of problems can arise (e.g., the distribution of power in a frame in terms of an RCPI (Received Channel Power Indicator) defined in IEEE 802.11 varies). Consequently, even when the lengths of data items transmitted to users are not the same, multiplexed frames on the same time axis need to be finally transmitted while retaining the same frame length.

[009] For example, in systems having a fixed frame format (such as an existing cellular system), a frame, for example, can be filled in by entering diversity data (refer to, for example, PTL 2), programming assigned times (refer to, for example, PTL 3), using a variable data rate (refer to, for example, PTL 4 or 5), or using a variable channel configuration (refer to, for example, PTL 6). However, since the configuration of such a system differs radically from the configuration of a system using a variable length frame format, such as a wireless LAN system, it is difficult to apply such existing technologies to the system using a length frame format variable.

Citation List Patent Literature

[0010] PTL1: Publication of Japanese Non-Examined Patent Application No. 2004-328570

[0011] PTL2: Publication of Japanese Non-Examined Patent Application No. 2001-148646

[0012] PTL3: Publication of Japanese Non-Examined Patent Application No. 2009-506679

[0013] PTL4: Publication of Japanese Non-Examined Patent Application No. 2008-236065

[0014] PTL 5: Japanese Patent No. 2855172

[0015] PTL 6: Publication of Unexamined Japanese Patent Application No. 2007-89113

[0016] EP1865672 A2 discloses a system in which a receiver and a plurality of terminals communicate simultaneously with each other under the SDMA scheme; the transmission parameters to be used to generate frames for SDMA transmission to the respective terminals are adjusted taking into account the transmission time necessary for the transmission of other frames to be transmitted simultaneously with the previously mentioned frames, so that the differences between the durations of the frame transmission times are reduced.

Description of the Invention Technical problem

[0017] It is an object of the present invention to provide excellent communication apparatus, communication method, computer program, and communication system capable of properly carrying out a communication operation using space division multiple access in which a plurality of users share wireless features on the space axis.

[0018] It is another object of the present invention to provide excellent communication apparatus, communication method, computer program, and communication system capable of multiplexing frames having a variable length frame format and intended for a plurality of users and optimally transmitting the paintings.

[0019] It is yet another object of the present invention to provide excellent communication apparatus, communication method, computer program, and communication system capable of adequately transmitting frames having a variable length frame format in a multiplexed manner while preventing a change abrupt in the total transmission power on the transmitter side even when the lengths of the transmission data items intended for a plurality of users are not the same.

Solution to the problem

[0020] In order to solve the problems described above, the present invention is provided. According to the invention described in claim 1, a communication apparatus includes a frame generation unit configured to generate a plurality of frames to be transmitted at the same time, a frame integration processing unit configured to integrate at least two of the frames generated by the frame generation unit in a single aggregate frame, means for filling in the aggregate frame if the length of the aggregate frame is shorter than the length of another frame that is multiplexed at the same time, and a communication unit configured to transmit frames at the same time in a multiplexed manner.

[0021] According to the invention described in claim 2, the communication apparatus according to claim 1 further includes a frame length control unit configured to adjust the lengths of a plurality of multiplexed frames at the same time so that the lengths finally become the same.

[0022] According to the invention described in claim 3, the frame length control unit of the communication apparatus according to claim 2 comprises at least two frames having short lengths in a single frame having a long length.

[0023] According to the invention described in claim 4, the communication unit of the communication apparatus according to claim 3 includes a plurality of antenna elements capable of functioning as an adaptive array antenna by assigning weights to the antenna elements and it can transmit a plurality of frames at the same time in a multiplexed manner. In addition, if the frame lengths are not the same, the frame length control unit determines which communication devices among the communication devices defined as the frame destinations can be combined based on the antenna weights and adjust the lengths of the antennas. of the boards integrating the boards intended for communication devices in the combination using the board integration processing unit.

[0024] According to the invention described in claim 5, if the frame length control unit of the communication apparatus according to claim 4 is finally unable to make the frame length the same through frame integration, the frame length control unit appropriately fills the frame having a short length so that the frames finally have the same length.

[0025] According to the invention described in claim 6, a communication method includes a frame generation step to generate a plurality of frames to be transmitted at the same time, a frame integration processing step to integrate at least two of the frames generated in the frame generation step in a single aggregate frame, a step to fill in the aggregate frame if the length of the aggregate frame is shorter than the length of another frame that is multiplexed at the same time, and a step of communication to transmit a plurality of frames at the same time in a multiplexed manner.

[0026] According to the invention described in claim 7, a computer program written in a readable format by comprising a program code to cause a computer to perform the steps of the communication method when the computer program is executed in a computer.

[0027] The computer program according to claim 7 defines a computer program written in a machine-readable format so that a predetermined process is carried out by a computer. That is, by installing the computer program according to claim 7 of the invention on a computer, cooperative processes are carried out on the computer. Accordingly, operations and advantages which are the same as those of the communication apparatus according to claim 1 of the invention can be obtained.

[0028] In addition, as used here, the term "system" refers to a logical combination of a plurality of devices (or functional modules which each performs a particular function); the plurality of devices or functional modules are not necessarily included in an appliance.

[0029] According to the invention described in claim 8, a communication system includes a first communication device configured to integrate at least two frames between a plurality of frames to be transmitted at the same time in a single frame and transmit the frames to the at the same time in a multiplexed manner and a plurality of second communication devices configured to receive the multiplexed frames at the same time.

Advantageous Effects of the Invention

[0030] In accordance with the present invention, communication apparatus, communication method, computer program, and excellent communication system capable of properly carrying out a communication operation using space division multiple access in which a plurality of users share wireless features on the space axis can be provided.

[0031] Further, according to the present invention, excellent communication apparatus, communication method, computer program, and communication system capable of adequately transmitting frames having a variable length frame format in a multiplexed manner while avoiding a abrupt change in the total transmission power on the transmitter side even when the lengths of transmission data items intended for a plurality of users are not the same can be provided.

[0032] According to the invention described in claims 1 and claims 6 to 8, when a communication device multiplexes a plurality of frames at the same time and transmits the frames, a process for integrating at least two frames between a plurality of frames in a single frame, that is, Aggregation, can be performed when needed. By employing a frame integration process in the space division multiple access scheme, the total number of multiplexed frames can be reduced. Consequently, the transmission power per communication station defined as a destination is increased on the transmission side, and an increase in the quality of the communication can be expected.

[0033] According to the invention described in claim 2, even when the frame lengths intended for users are not the same when a transmission request is delivered from an upper layer, the multiplexed frames at the same time can finally be made. and can be transmitted. Consequently, frames having a variable length frame format can be multiplexed and appropriately transmitted while avoiding an abrupt change in the total transmission power on the transmission side. As a result, on the receiving side that receives the multiplexed frames, an unstable AGC operation due to an abrupt change in the received power can be avoided.

[0034] According to the invention described in claim 3, by integrating at least two frames having short lengths into one frame having a long length, the multiplexed frames at the same time can finally have the same length and can be transmitted. Consequently, frames having a variable length frame format can be appropriately multiplexed and transmitted while avoiding an abrupt change in the total transmission power on the transmission side. As a result, on the receiving side that receives the multiplexed frames, an unstable AGC operation due to an abrupt change in the received power can be avoided.

[0035] According to the invention described in claim 4, in a communication device that performs multiple access by space division using an adaptive array antenna, extracting, among communication devices defined as destinations of a plurality of frames transmitted in in a multiplexed manner, a combination of the communication apparatus suitable for combining the antenna weights, the frame integration processing unit can integrate the frames intended for the communication apparatus in the combination and adjust the length of the frames. That is, by combining frame aggregation with the space division multiple access scheme, overhead can be reduced and the communication transmission capacity from one to many can be increased at the same time.

[0036] According to the invention described in claim 5, even when the lengths of the frames cannot finally be made the same through integration of the frames, the lengths of the frames can finally be made the same through a filling process carried out in the frames having short lengths as needed. Therefore, the transmission power per frame can be increased by reducing the total number of multiplexed frames through Frame Aggregation. In addition, by making the frame lengths the same, unstable AGC operation on the receiver side can be avoided.

[0037] Additional features and advantages of the present invention will become apparent from the following detailed description of the exemplary embodiments of the present invention with reference to the attached drawings.

Brief Description of Drawings

[0038] [Fig. 1] Fig. 1 is a schematic illustration of the configuration of a communication system according to an embodiment of the present invention.

[0039] [Fig. 2] Fig. 2 illustrates an example of the configuration of a communication device capable of multiplexing a plurality of users through multiple access by space division.

[0040] [Fig. 3] Fig. 3 illustrates an example of the configuration of a communication device that complies with an existing standard, such as IEEE 802.11a, and that does not use space division multiple access.

[0041] [Fig. 4] Fig. 4 illustrates an example of a processing sequence of the communication system illustrated in Fig. 1 in which the communication station STA0 operating as an access point serves as a data source, communication stations STA1 to STA3 operating as client devices serve as data destinations, and STA0 multiplex frames to be transmitted to communication stations STA1 to STA3 on a spatial axis and transmit the frames at the same time.

[0042] [Fig. 5] Fig. 5 illustrates frames A and B that have different lengths and that are multiplexed on the same time axis.

[0043] [Fig. 6] Fig. 6 illustrates the case in which when a plurality of frames having different lengths are multiplexed at the same time, the frames are subjected to a filling process.

[0044] [Fig. 7] Fig. 7 illustrates the case in which at least two frames having short lengths are integrated into a single frame by Aggregation so that the frame lengths are adjusted with respect to the length of a frame having a long length.

[0045] [Fig. 8] Fig. 8 is a flowchart of a processing sequence performed by the communication device illustrated in Fig. 2 when, in the communication sequence illustrated in Fig. 7, the communication device functions as an access point (STA0) and transmits frames destined for a plurality of communication stations at the same time in a multiplexed manner.

[0046] [Fig. 9] Fig. 9 is a flow chart of a processing sequence performed by the communication device illustrated in Fig. 2 when, in the communication sequence illustrated in Fig. 7, the communication device works like any of the client devices (STA1 to STA3 ) and receives frames transmitted from an access point at the same time in a multiplexed manner.

Description of Modalities

[0047] Modalities of the present invention are described in detail below with reference to the accompanying drawings.

[0048] Fig. 1 is a schematic illustration of the configuration of a communication system according to an embodiment of the present invention. The communication system illustrated in the drawing includes a communication station STA0 operating as an access point (AP) and a plurality of communication stations STA1, STA2, and STA3 each operating as a client device (MT).

[0049] The communication area of each of the communication stations STA1, STA2, and STA3 includes the communication station STA0, and each of the communication stations STA1, STA2, and STA3 can directly communicate with the communication station STA0 (that is, the communication stations STA1, STA2, and STA3 are controlled by the communication station STA0 serving as an access point and form a BSS (Basic Service Set)). However, each of the communication stations STA1, STA2, and STA3 serving as client devices need to be located within the communication areas of the other communication stations. Henceforth, direct communication between client devices is not discussed.

[0050] Here, the STA0 communication station serving as an access point is made up of a communication device that includes a plurality of antennas and performs multiple access by dividing space using an adaptive array antenna. The STA0 communication station allocates wireless resources on the space axis to a plurality of users and multiplexed frame communication. That is, the STA0 communication station is a communication device that complies with a new standard such as IEEE 802.11ac. The STA0 communication station multiplexes two or more frames destined for different communication stations on the same time axis and separates a frame destined for the STA0 communication station and multiplexed for two or more communication stations in frames for the originating communication stations. In this way, the communication station STA0 performs frame communication from one to many. The STA0 communication station can increase the number of client devices capable of multiple access by dividing space by increasing the number of antennas on it. Of course, in addition to performing one-to-many frame communication with the STA1, STA2, and STA3 communication stations using multiple space division access, the STA0 communication station can perform point-to-point communication with each of the communication stations STA1, STA2, and STA3.

[0051] In contrast, each of the communication stations STA1, STA2, and STA3 serving as a client device is made up of a communication device that includes a plurality of antennas and performs multiple access by dividing space using a matrix antenna adaptive. However, user separation is performed only when a reception operation is performed. When a transmission operation is performed, user separation, that is, multiplexing of transmission frames is not performed. Consequently, the number of antennas may be less than that of the access points. Note that at least some of the client devices under the control of the STA0 communication station serving as an access point may be communication devices that conform to the existing standard, such as IEEE 802.11a. That is, the communication system illustrated in Fig. 1 is in an environment in which communication devices that match the new standard coexist with communication devices that match an existing standard.

[0052] Fig. 2 illustrates an example of the configuration of a communication device capable of multiplexing a plurality of users through multiple access by space division. Between the communication stations in the communication system illustrated in Fig. 1, the communication station STA0 serving as an access point and any of the communication stations STA1 to STA3 that serve as a client device and that employs the multiple access scheme per space division has a configuration illustrated in Fig. 2 and performs a communication operation according to the new standard.

[0053] The communication apparatus illustrated in the drawing includes N transmission and reception branches 20-1, 20-2, ..., and 20-N having antenna elements 21-1, 21-2, ..., and 21-N, respectively, and a data processing unit 25 connected to the transmit and receive branches 20-1, 20-2, ..., and 20-N (where N is an integer greater than or equal to 2 ). The data processing unit 25 processes data to be transmitted and data received. When appropriate weights for an adaptive array antenna are assigned to a plurality of antenna elements 21-1, 21-2, ..., and 21-N, antenna elements 21-1, 21-2, ... , and 21-N can function as an adaptive array antenna. The STA0 communication station serving as the access point performs multiple access by space division using the adaptive array antenna. By increasing the number of antenna elements included in it, the STA0 communication station can increase the number of client devices included in multiple access.

[0054] In the transmission and reception branches 20-1, 20-2, ..., and 20- N, the antenna elements 21-1, 21-2, ..., and 21-N are connected to the units transmit processing units 23-1, 23-2, ..., and 23-N and receive processing units 24-1, 24-2, ..., and 24-N via duplexers 22-1, 22- 2, ..., and 22-N, respectively.

[0055] The data processing unit 25 generates data to be transmitted in response to a transmission request received from an upper layer application and, thereafter, classifies the data in the transmission and reception branches 20-1, 20 -2, ..., and 20-N. In addition, at the communication station STA0 serving as an access point, the data processing unit 25 generates a plurality of data items to be transmitted to a plurality of users, that is, data items to be transmitted to the stations. of communication STA1, STA2, and STA3 in response to a transmission request received from an upper layer application and thereafter multiplies the data items by an adaptive array antenna transmission weight for each of the branches of transmission and reception. In this way, the data items are spatially separated and classified into the transmit and receive branches 20-1, 20-2, ..., and 20-N. Note that as used here, the term "spatial separation" in transmission refers only to user separation in which frames transmitted at the same time are spatially separated for users.

[0056] Each of the transmission processing units 23-1, 23-2, ..., and 23-N performs predetermined signal processing, such as coding and modulation, on a digital baseband transmission signal provided to from data processing unit 25 and thereafter performs D / A conversion on the digital baseband transmission signal. Subsequently, each of the 23-1, 23-2, ..., and 23-N transmission processing unit converts the digital baseband transmission signal upward into an RF (Radio Frequency) signal. Therefore, the signal strength is amplified. Subsequently, such transmit RF signals are supplied to the antenna elements 21-1, 21-2, ..., and 21-N via the duplexers 22-1, 22-2, ..., and 22-N. Therefore, the transmitting RF signals are emitted in the air.

[0057] On the contrary, when receiving RF reception signals from antenna elements 21-1, 21-2, ..., and 21-N via duplexers 22-1, 22-2, ... , and 22-N, the reception processing units 24-1, 242, ..., and 24-N amplify RF reception signals with low noise. Thereafter, the reception processing units 24-1, 24-2, ..., and 24-N down-convert RF reception signals into analog baseband signals and convert analog signals from A / D base band. Furthermore, the reception processing units 24-1, 24-2, ..., and 24-N perform predetermined signal processing, such as decoding and modulation removal, on analog baseband signals.

[0058] Data processing unit 25 multiplies the digital reception signal input from each of the reception processing units 24-1, 24-2, ..., and 24-N by an antenna receiving weight adaptive matrix and performs separation. In this way, the transmission data items transmitted from the users, that is, from the communication stations STA1, STA2, and STA3, are reconstructed. Thereafter, data processing unit 25 delivers the reconstructed transmission data items to an upper layer application. Note that as used here, the term "spatial separation" at reception refers to user separation in which frames transmitted at the same time are spatially separated for users and channel separation in which a spatially multiplexed MIMO channel is separated into the original multiple strings .

[0059] At that time, in order to cause the antenna elements 211, 21-2, ..., and 21-N to work with an adaptive array antenna, the data processing unit 25 controls the data processing units transmission 23-1, 23-2, ..., and 23-N and the receiving processing units 24-1, 24-2, ..., and 24-N so that the transmission data items classified in transmit and receive branches 20-1, 20-2, ..., and 20-N are multiplied by the transmit weights of the adaptive array antenna and received data items received from the transmit and receive branches 20-1 , 20-2, ..., and 20-N are multiplied by the reception weights of the adaptive matrix antenna. In addition, before performing multiple space division access with the communication stations STA1, STA2, and STA3, the data processing unit 25 learns the weights of the adaptive matrix antenna. For example, data processing unit 25 can learn the weights of the adaptive array antenna using training signals (described in more detail below) received from communication partners STA1, STA2, and STA3 in a known sequence and a predetermined algorithm adaptive, such as an RLS (Minimum Recursive Square) algorithm.

[0060] For example, the data processing unit 25 performs a process in each of the layers of a communication protocol of a Media Access Control (MAC) technique implemented in the communication system illustrated in Fig. 1. In addition, for example, the transmit and receive branches 20-1, 20-2, ..., and 20-N perform a process corresponding to a PHY layer. As described below, frames having different lengths are transmitted from an upper layer. At that time, the lengths of the frames finally transmitted from the PHY layer are made the same. Note that such control of the frame lengths can be performed by either the data processing unit 25 or the transmit and receive branches 201, 20-2, ..., and 20-N.

[0061] Note that each of the communication stations STA1, STA2, and STA3 serving as client devices has a plurality of antennas and performs multiple access by space division using an adaptive array antenna. At that time, each of the communication stations STA1, STA2, and STA3 performs user separation only at the reception and does not effect user separation in the transmission, that is, transmission frame multiplexing. Consequently, each of the communication stations STA1, STA2, and STA3 need not have as many antennas as the access point.

[0062] In addition, Fig. 3 illustrates an example of the configuration of a communication device that complies with an existing standard, such as IEEE 802.11a, and that does not use the space division multiple access scheme. Among the client devices under the control of the STA0 communication station serving as an access point in the communication system illustrated in Fig. 1, a client device that has a configuration illustrated in Fig. 3 and which performs communication according to only one standard existing is present.

The communication apparatus illustrated in the drawing includes a transmit and receive branch 30 having an antenna element 31 and a data processing unit 35 which is connected to the transmit and receive branch 30 and which processes data to be transmitted and received data. In addition, on the transmit and receive branches 30, the antenna element 31 is connected to a transmit processing unit 33 and a receive processing unit 34 via a duplexer 32.

[0064] The data processing unit 35 generates data to be transmitted in response to a transmission request received from an upper layer application and, thereafter, sends the data to the transmit and receive branch 30. The unit transmission processing 33 performs predetermined signal processing, such as encoding and modulation, on a digital baseband transmission signal and thereafter performs D / A conversion on the digital baseband transmission signal. Subsequently, the data processing unit 35 converts the digital baseband transmission signal upward into an RF signal. Therefore, the signal strength is amplified. Subsequently, such a transmit RF signal is supplied to the antenna element 31 via duplexer 32. Thereafter, the transmit RF signal is emitted in the air.

On the contrary, when receiving the RF reception signal from the antenna element 31 via the duplexer 32, the receiving processing unit 34 amplifies the RF reception signal with low noise. Thereafter, the receiving processing unit 34 converts the RF reception signals down to an analog baseband signal and converts the analog baseband signal from A / D. In addition, the receiving processing unit 34 performs predetermined signal processing, such as predetermined decoding and modulation removal, on the analog baseband signal. The data processing unit 35 reconstructs the original transmission data from the input of the digital reception signal from the reception processing unit 34 and delivers the original transmission data to an upper layer application.

[0066] In the communication system illustrated in Fig. 1, the communication station STA0 serving as an access point multiplies a plurality of antenna elements 21-1, 21-2, ..., and 21-N by the weights of an adaptive array antenna. Therefore, the communication station STA0 causes the antenna elements 21-1, 21-2, ..., and 21-N to function as an adaptive array antenna. In this way, routing capabilities for communication stations STA1 to STA3 can be formed. As a result, the wireless resources on the space axis can be separated for users, and a plurality of frames destined for communication stations STA1 to STA3 can be multiplexed and transmitted at the same time. In addition, functioning as an adaptive matrix antenna, the communication station STA0 can separate the frames transmitted from the communication stations STA1 to STA3 at the same time for users and carry out a reception process.

[0067] At that time, in order for the antenna elements 21-1, 212, ..., and 21-N to function as an adaptive array antenna, the weights of the adaptive array antenna need to be learned in advance. For example, the communication station STA0 can learn the weights of the adaptive matrix antenna by acquiring a transfer function from training signals received from communication stations STA1 to STA3 in a known sequence. Alternatively, the STA0 communication station can directly learn the weights of the adaptive array antenna using training signals received from a plurality of communication partners in a known sequence and a predetermined adaptive algorithm, such as an RLS (Recursive Minimum Square).

[0068] In both of the techniques described above, the STA0 communication station that learns the weights of an adaptive matrix antenna needs to receive training signals from the STA1 to STA3 communication stations. In addition, in a communication environment in which a communication device that matches only an existing standard exists, a normal frame switching sequence needs to be performed while avoiding carrier collision. Similarly, training signals need to be transmitted while avoiding interference with the communication device that matches only an existing standard. That is, the STA0 communication station needs to learn the weights of the adaptive array antenna while maintaining downward compatibility with the existing standard.

[0069] Fig. 4 illustrates an example of a communication sequence for learning the weights of the adaptive matrix antenna using training signals. In the example illustrated in the drawing, the learning communication station transmits a Training Request (TRQ) frame to request transmission of a training signal. Upon receipt of the TRQ board, each of the neighboring stations returns a training board including a known sequence used for the training process. Note that although the STA4 communication station in Fig. 4 is not shown in Fig. 1, the STA4 communication station is a communication station that matches only an existing standard and this is a hidden terminal located in at least one of the areas communication from communication stations STA0 to STA3.

[0070] The STA0 communication station serving as an access point senses the physical carrier in advance and confirms that a means is clear. Furthermore, the communication station STA0 performs a waiting process for a random time interval and transmits a TRQ frame. At that time, the STA0 communication station has not yet learned the weights of the adaptive array antenna (ie, the antenna elements 21-1, 21-2, ..., and 21-N do not yet have a function as the antenna of adaptive matrix). Consequently, the communication station STA0 transmits the TRQ frame in all directions in 360 degrees.

[0071] The TRQ framework includes a field that complies with IEEE 802.11, which is an existing standard. The field contains duration information that asks the communication device that is not a destination of the TRQ board (the hidden terminal) to configure, in NAV, a counter value corresponding to a duration until a signal transmission and reception sequence is completed.

[0072] When receiving a TRQ frame that does not include a destination indicating the STA4 communication station, the STA4 communication station that matches an existing standard NAV counter value using the duration information included in the frame. Therefore, the STA4 communication station does not carry out a transmission operation.

[0073] In addition, according to the sketch of the communication stations illustrated in Fig. 1, the TRQ frame transmitted from the communication station STA0 reaches each of the communication stations STA1 to STA3. In response to the received TRQ frame, after a predetermined frame interval SIFS (Short Frame Space) has passed since the TRQ frame including a destination indicating the communication station has been received, each of the communication stations STA1 to STA3 returns a training framework including a known usable sequence for training the adaptive array antenna.

[0074] In accordance with the present modality, learning the weights of the adaptive matrix antenna is performed while maintaining compatibility in the downward direction with an existing standard. Therefore, the training board has a front field and a rear field. The front field complies with IEEE 802.11, which is an existing standard. The rear field contains a known sequence for training and has no downward compatibility with the existing standard. In order to stop a transmission operation to neighboring stations that match the existing standard that completes a series of transmission and signal reception operations, mystification described in the drawing is performed in the front field that matches the existing standard so that the error of interpretation that the training framework continues until subsequently completed ACK transmission is completed. Note that the mystification technique is described in more detail in, for example, Unexamined Japanese Patent Application Publication No. 2008-252867 whose patent rights have already been assigned to the applicant for the present invention.

[0075] In addition, in the example illustrated in Fig. 4, the communication stations STA1 to STA3 transmit the training frames at the same time.

[0076] At that time, training frames can be transmitted in a multi -plexed manner over time. However, if the training frames are transmitted in a multiplexed manner over time, a period of time required for transmission of all training frames (ie, a transmission delay time required for each of the neighboring stations) increases with an increase the number of communication stations that send the training boards back (ie, the number of communication stations to be learned). Consequently, the transmission capacity of the complete system decreases, and the system overhead increases. In addition, the neighboring station that can receive only one training frame transmitted at a later time on the time axis (the hidden terminal) can start an operation before the training frame arrives, as the NAV counter value disappears. Therefore, carrier collision cannot be avoided. For these reasons, according to the present modality, the training frames are transmitted at the same time.

[0077] On the contrary, after transmission of the TRQ board has been completed, the communication station STA0 enters a standby mode until the training boards transmitted from communication stations STA1 to STA3, which are destinations of the communication board TRQ, be received. When the training board is received, the STA0 communication station has not yet learned for the adaptive array antenna. Consequently, the STA0 communication station needs to receive a plurality of training frames at the same time using any of the antenna elements. At that time, if the following three conditions are met, the STA0 communication station can receive the front field sections of the training fields transmitted at the same time (the front field sections having reverse direction compatibility with the existing standard) while avoiding collision . (1) Employ an OFDM modulation technique. (2) Operate the oscillators of the communication stations STA1, STA2, and STA3 so that a frequency error with respect to the oscillator used in the communication station STA0 is compensated. (3) Make information items in the fields of the training boards transmitted from the communication stations STA1, STA2, and STA3 the same.

[0078] It is known that the OFDM modulation technique suggested in condition (1) has advantages including its robustness for multipath fading. In addition, condition (2) can be satisfied if the communication stations STA1, STA2, and STA3 perform frequency correction when receiving a TRQ frame from the communication station STA0. By making frequency correction, it is ensured that the delay times when the training frames transmitted from the communication stations STA1, STA2, and STA3 at the same time reach the communication station STA0 are within a protection interval. Furthermore, as condition (3) implies, if some information items in the fields of the communication stations STA1, STA2, and STA3 are the same, these fields can be treated as a normal delay wave. Therefore, training frames can be received at the same time using the single antenna element.

[0079] In addition, the STA0 communication station receives the rear field of the training board which contains a known sequence for training and which does not have reverse direction compatibility with the existing standard using the antenna elements 21-1, 21-2 , ..., and 21-N. By assigning a particular code sequence from each of the communication stations STA1, STA2, and STA3 as the known sequence for training in advance, the communication station STA0 can spatially separate the sequences. However, if the number of communication stations that perform multiple access by space division through space division is increased, the length of the known sequence inevitably increases since the communication stations need to be distinguished from each other.

[0080] Subsequently, the communication station STA0 learns the weights of the adaptive array antenna using the known sequences and a predetermined adaptive algorithm, such as the RLS algorithm. Thereafter, the antenna elements 21-1, 21-2, ..., and 21-N of the STA0 communication station can function as an adaptive array antenna, and the STA0 communication station can perform multiple access via space division.

[0081] On the contrary, upon receipt of the training framework described above that does not include STA4 as the destination, the STA4 communication station that matches only the existing standard does not understand that the training framework continues until the subsequent ACK framework is transmitted due to mystification (as described above). Therefore, the STA4 communication station does not carry out a transmission operation.

[0082] After a predetermined frame interval SIFS has passed since the communication station STA0 received the training frames sent from the communication stations STA1, STA2, and STA3, the communication station STA0 transmits data frames (Fragment0- 1, Fragment0-2, and Fragment0-3) for communication stations STA1, STA2, and STA3, respectively. Using the learned weights described above from the adaptive array antenna, the STA0 communication station can transmit a plurality of data frames through multiple space division access at the same time.

[0083] On the contrary, when receiving the data frames (Fragment0-1, Fragment0-2, and Fragment0-3) destined for the communication stations STA1, STA2, and STA3, the communication stations STA1, STA2, and STA3 send back ACK frames (ACK1, ACK2, and ACK3), respectively, at the same time after the predefined SIFS frame interval has passed.

[0084] The plurality of antenna elements 21-1, 21-2, ..., and 21-N of the STA0 communication station has already functioned as an adaptive antenna. Consequently, the communication station STA0 can spatially separate a plurality of ACK frames (ACK1, ACK2, and ACK3) received at the same time for each of the users. For example, by storing, in the ACK frames, the addresses of the communication stations STA1, STA2, and STA3 as addresses of the transmitter, the communication station STA0 can identify the origin of the received ACK frames. In addition, if the known training sequences are stored in the same ACK frames, the STA0 communication station can change the weights learned from the adaptive array antenna according to the known training sequences stored in the received ACK frames so that the weights can adaptively follow a change in the environment.

[0085] When receiving the data frames that are not destined for the STA4 communication station, the STA4 communication station that conforms to the existing standard sets a NAV counter value on the basis of the duration information contained in the table. In this way, the communication station STA4 stops a transmission operation. In addition, upon receipt of the ACK frame that is not intended for the STA4 communication station, the STA4 communication station that conforms to the existing standard sets a NAV counter value on the basis of the duration information contained in the frame. In this way, the communication station STA4 stops a transmission operation.

[0086] As can be seen from an example of the communication sequence illustrated in Fig. 4, the STA0 communication station that performs multiple access by space division can appropriately learn the weights of the adaptive matrix antenna. Furthermore, after the STA0 communication station has learned the weights of the adaptive array antenna, the STA0 communication station can share wireless resources on a spatial axis with a plurality of users and multiplex a plurality of data frames intended for a plurality of users. Thereafter, the STA0 communication station can transmit the data frames. In this way, the transmission capacity can be increased in the case of one to many communication, that is, communication between a plurality of users.

[0087] In this case, in general, a wireless LAN employs a packet communication scheme. The amounts of traffic that users want to differ from user to user. Therefore, the packet lengths (frames) differ from each other. For example, in the example of a communication sequence illustrated in Fig. 4, it is desirable that the lengths of a TRQ board, a training board, and an ACK board are the same. However, for a plurality of data frames transmitted from the STA0 communication station, the lengths of the frames transmitted from the MAC layer to the PHY layer may not be the same due to the difference in the amount of data transmitted from the destination the destination.

[0088] However, when frames intended for a plurality of users are multiplexed and, simultaneously, transmitted through the multiple access scheme by space division and if the total transmission power is abruptly changed due to a difference between the lengths of frames, an unstable AGC operation can disadvantageously occur on the receiver side due to an abrupt change in the received power (as described above).

[0089] In addition, if any of the frames to be multiplexed are terminated and the other frames continue to be transmitted, the communication bandwidth is not used efficiently. Therefore, the effect of multiple access by space division is lessened. Fig. 5 illustrates frames A and B that have different lengths and that are multiplexed on the same time axis. As can be seen in the example illustrated in the drawing, the length of frame B is shorter than the length of frame A, and after transmission of frame B has been completed, the communication bandwidth is consumed.

[0090] Therefore, even when the lengths of the multiplexed frames at the same time differ from each other, all the transmitted frames must finally have the same frame length.

[0091] For example, between spatially multiplexed frames, frames having short lengths can be filled in the PHY layer so that the lengths of the frames are made the same. Fig. 6 illustrates the case in which, in the example of the communication sequence illustrated in Fig. 4, when data to be transmitted to STA1 to STA3 at the same time are delivered from the largest layer (eg, the MAC layer) and the quantity of each of the data items to be transmitted to STA2 and STA3 (DATA2 and DATA3) is less than that of some data items to be transmitted to STA1 (DATA1), the data items to be transmitted to STA2 and STA3 (DATA2 and DATA3) are filled in so that each of the lengths of DATA2 and DATA3 is the same as the length of the data items having a longer length (DATA1). Therefore, the lengths of the frames finally transmitted from the PHY layer are made the same.

[0092] However, the filling operation causes overhead since actual data are not included. Therefore, it is desirable that the frame lengths are adjusted without using a fill operation.

[0093] Consequently, the present inventors have developed a technique for adjusting the lengths of two or more frames having short lengths so that the lengths match the lengths of a frame having a long length by integrating the frames into a single frame through Aggregation. In IEEE 802.11n for high-speed communication, the term "Aggregation" is known as a frame format that reduces overhead by configuring a single physical layer section from a plurality of frames.

[0094] Fig. 7 illustrates the case in which, in the example of the communication sequence illustrated in Fig. 6, when data to be transmitted to STA1 to STA3 at the same time are delivered from an upper layer (eg, the MAC layer) and if a quantity of each of the data items to be transmitted to STA2 and STA3 (DATA2 and DATA3) is less than that of the data items to be transmitted to STA1 (DATA1), the data items to be transmitted to STA2 and STA3 ( DATA2 and DATA3) are integrated into a single frame by Aggregation so that the length of DATA2 and DATA3 is the same as the length of data items having a longer length (DATA1). Therefore, the lengths of the frames finally transmitted from the PHY layer are made the same.

[0095] Upon receipt of an Aggregation table, each of the communication stations can refer to the destination information contained in the top portion of the table and extract the portion of data destined for the communication station. For example, when receiving the Aggregation frames including data items destined for STA2 and STA3, each of the communication stations STA2 and STA3 recognizes that the frame includes some data items destined for them even using the destination information in the portion of top of the frame and determines which data items in the frame are intended for them even using the header information attached to each of the data items. In this way, each of the communication stations STA2 and STA3 retrieves the desired data items.

[0096] The STA0 access point can employ a scheme in which the MIMO antenna weight used when an Aggregation frame is transmitted is determined as the sum of the MIMO antenna weights used when the STA0 access point individually transmits a frame for all communication stations. In the example of the communication sequence illustrated in Fig. 6, since the transmission power used for the communication stations is divided for the communication stations STA1, STA2, and STA3, each transmission power is a third of the total power. On the contrary, in the example of the communication sequence illustrated in Fig. 7, the data items destined for STA2 and STA3 are submitted to the Aggregation, the power required for the two communication stations does not need to be separated. That is, using Aggregation in a space division multiple access scheme, the transmission power used for each of the communication stations is reduced to one half of the total power. Therefore, the quality of communication can be increased.

[0097] In addition, as shown in Fig. 7, after the STA1 to STA3 communication stations that receive the Aggregation frames complete the reception of all Aggregation frames, the STA1 to STA3 communication stations send back ACK frames (ACK1, ACK2, and ACK3) destined for STA0, which is the origin of the Aggregation tables, at the same time. For the returned ACK frames, the antenna elements 21-1, 21-2, ..., and 21-N of the STA0 communication station have already functioned as an adaptive antenna. Consequently, the antenna elements 21-1, 212, ..., and 21-N can spatially separate the plurality of ACK frames (ACK1, ACK2, and ACK3) received at the same time for each of the users (as described above) ).

[0098] Fig. 8 illustrates a processing sequence in the form of a flow chart in which, in the communication sequence illustrated in Fig. 7, the communication apparatus illustrated in Fig. 2 functions as the access point (STA0) and transmits frames intended for a plurality of communication stations at the same time in a multiplexed manner. The access point starts the processing sequence illustrated in Fig. 8 in response to, for example, the occurrence of a data transmission request or a data reception request from an upper layer application.

[0099] The access point examines that the medium is free by performing a physical carrier sensing in advance and still performs a waiting process for a random duration interval. In this way, if the access point enters a communicable mode, the access point transmits a training request frame (TRQ) to one or more communication stations (STA1 to STA3) to which the access point wants to transmit data in a multiplexed manner (step S1).

[00100] Subsequently, after a predetermined frame interval SIFS (Short Frame Space) has passed since the TRQ frame has been transmitted, the access point waits until it receives training frames sent back from the request request recipients. training (STA1 to STA3) (step S2).

[00101] At that time, if the access point was not received a training frame from any of the recipients of the training request (STA1 to STA3) (NOT in step S3), the processing proceeds to a process of relaying the TRQ framework. However, the details of the frame retransmission process are not provided here.

[00102] However, if the access point can receive a training frame from at least one of the recipients of the training request (STA1 to STA3) (YES in step S3), the access point learns the weights of the antenna from adaptive matrix using the known training sequence included in each of the training frames received.

[00103] Thereafter, the access point determines whether the lengths of the multiplexed frames destined for the communication stations from which the access point was able to receive the training frames are the same (step S4).

[00104] Here, if the lengths of the frames to be multiplexed are the same (YES in step S4), the access point directly multiplexes the data frames destined for the communication stations from which the access point was able to receive the training frames and transmit the data frames after a predefined SIFS frame interval has passed since the training frames have been received. Thereafter, this processing routine is completed.

[00105] At that time, using the weights learned from the adaptive matrix antenna, the access point can transmit the data frames destined for the plurality of client devices at the same time through space division multiplexing. However, the access point does not transmit the data frames to the client device from which the access point has not received a training frame, since learning is not done for the client device and it is doubtful as to whether the client device is or is not present within the communication area.

[00106] However, if the lengths of the frames to be multiplexed are not the same (NOT in step S4), the access point determines whether among the plurality of communication stations that are destinations of the multiplexed frames (STA1 to STA3), a appropriate combination to match the antenna weights is present (eg, a combination of communication stations located in the vicinity is present) (step S5).

[00107] At that moment, one of the techniques to determine if a combination of the communication stations located in the neighborhood is present is to compare the values of the antenna weights of the communication stations each with the other. That is, the access point can determine whether the antenna weight values of one of the communication stations are close to those of another communication station as a predetermined reference. If the antenna weight values of the communication stations are close to each other, the access point can determine that a combination of the communication stations is appropriate. For example, let STA0 have three antennas. In addition, a combination of the antenna weights of the STA1 communication station indicates that the weight of an antenna 1 is large, the weight of an antenna 2 is half, and the weight of an antenna 3 is small. A combination of the antenna weights of the STA2 communication station indicates that the weight of the antenna 1 is large, the weight of the antenna 2 is small, and the weight of the antenna 3 is half. A combination of the antenna weights of a STA3 communication station indicates that the weight of antenna 1 is large, the weight of antenna 2 is small, and the weight of antenna 2 is half. So, since the values of the STA2 weights are close to the values of the STA3 weights, it can be determined that STA2 is appropriately combined with STA3. In addition, another technique for determining whether a combination of communication stations is a combination of communication stations located in the neighborhood is to determine whether the locations of communication stations are in the vicinity on the basis of the information provided by GPSs (Global Positioning Systems) mounted on the communication stations and determine that the combination of the communication stations located within a distance that satisfies a predetermined reference is appropriate.

[00108] If a combination of the appropriate communication stations to match the antenna weights is found (YES in step S5), it is determined whether the lengths of all frames destined for the communication stations in the combination and multiplexed at the same time made by performing Aggregation (step S6).

[00109] Thereafter, if the lengths of all multiplexed frames at the same time can be made the same by performing Aggregation (YES in step S6), an Aggregation process is carried out in the frames of a plurality of users (step S7). More specifically, the MIMO antenna weights which are the sums of the MIMO antenna weights used when the access point individually transmits a frame to all communication stations that are the destinations of the aggregate frames, are employed.

[00110] Thereafter, if the length of the Aggregate frame is not completely the same as the length of another frame that is multiplexed at the same time, one of the frames is appropriately filled so that the lengths of all frames are made as same (step S8).

[00111] However, if a combination of the appropriate communication stations to match the antenna weights is not found (NOT in step S5) or if the lengths of all frames cannot be made the same when Aggregation is performed (NOT in step S6), the aggregation of frames for multiple users is stopped, and the lengths of all frames are made the same using only one filling process (step S8).

[00112] Subsequently, after the predetermined frame interval SIFS has passed since training frames have been received, the frames submitted for adjusting the length of the frames are transmitted in a multiplexed manner. Thereafter, this processing routine is completed.

[00113] Fig. 9 illustrates a processing sequence in the form of a flowchart in which, in the communication sequence illustrated in Fig. 7, the communication apparatus illustrated in Fig. 2 operates like any of the client devices (STA1 to STA3) and receives multiplexed frames at the same time from the access point. At that moment, when receiving a TRQ frame from the access point (STA0), each of the client devices (STA1 to STA3) starts the processing sequence illustrated in Fig. 9. Note that at that moment, each of the client devices correct a frequency error using, for example, L-LTF from the header portion of the received TRQ frame, and it is ensured that timing error between client devices is within a guard interval.

[00114] After a predefined SIFS frame interval has passed from the client device received the TRQ frame from the access point (YES in step S11), the client device sends back a training frame to the access point ( step S12).

[00115] At that moment, the client device corrects a frequency error using the received TRQ frame. Consequently, when a plurality of client devices that send training frames back are present, it is ensured that the times when training frames arrive at the access point are within the guard interval. Therefore, the access point can receive a plurality of training frames at the same time using a single antenna element.

[00116] Subsequently, after the predefined SIFS frame interval has passed since the client device transmitted the TRQ frame (YES in step S13), the client device enters a standby mode until a data frame transmitted from the access point to be received. (step S14).

[00117] At that time, if the client device cannot receive a data frame or if the client device cannot decode a received data frame due to a frame error (NOT in step S15), the client device determines that reception of data a data frame is flawed. Therefore, this processing routine is completed. Alternatively, the client device can transmit NACK to the access point in order to ask the access point to relay the data frames.

[00118] However, when the client device can receive a data frame from the access point (SIM in step S15) and if the predefined SIFS frame interval has passed since the data frames have been received (SIM in step S16), the client device sends an ACK frame back to the access point (step S17). In this way, this processing routine is successfully completed.

[00119] As can be seen from Figs. 7 and 8, in the communication system according to the present modality, even when the frame lengths for users are not the same at a point in time when the communication device receives a transmission request from an upper layer application, the communication device can integrate at least two frames having short lengths into one frame having a long length through Aggregation and finally transmits the frames having the same frame lengths after multiplexing the frames at the same time.

[00120] The term "Aggregation" refers to a frame format to reduce excess by configuring a portion of data from the physical layer of a plurality of frames in IEEE 802.11n considering high-speed communication. According to the present modality, integrating frame aggregation in a multiple access scheme by space division, excess can be reduced and a high transmission capacity can be obtained in one-to-many communication.

[00121] In addition, when the communication device multiplexes a plurality of frames having a variable length format at the same time, the communication device adjusts the length of the frames so that the length of the frames are the same. In this way, an abrupt change in the total transmission power can be avoided. On the receiver side of the multiplexed frames, an unstable AGC operation caused by an abrupt change in the received power can be avoided. Even more, since, in terms of the Aggregation frame, the number of frames to be multiplexed can be reduced, the transmission power used by the destination communication device on the transmitter side can be increased. Therefore, an increase in the quality of communication can be expected.

[00122] Industrial Applicability

[00123] While the present invention has been described in detail with reference to the particular modalities, various modifications and alterations of this invention will become apparent to those skilled in the art without departing from the scope and principles of this invention.

[00124] While the present specification has been described with reference to modalities employing a new standard of wireless LAN s such as IEEE 802.11ac for the purpose of ultra high transmission capacity (1 Gbps), the scope of the invention is not limited to this. For example, the present invention is similarly applicable to another wireless LAN system in which wireless resources on a space axis are shared by a plurality of users and a variety of wireless systems other than a LAN.

[00125] That is, it is understood that the modalities described herein are for illustrative purposes only and the above description is not intended to be limiting. The scope of the invention must be determined by the appended claims. List of Reference Signals 20-1, 20-2, transmit and receive branch 21-1, 21-2, antenna element 22-1, 22-2, duplexer 23 -1, 23-2, transmission processing unit 24-1, 24-2, receiving processing unit 25 data processing unit 30 transmitting and receiving branch 31 antenna element 32duplexer 33 transmission processing unit 34 receiving processing unit 35 data processing unit

Claims (8)

1. Communication device comprising: a frame generation unit (20-1, 20-2, ..., 20-N, 25) configured to generate a plurality of frames to be transmitted at the same time; a frame integration processing unit (20-1, 20-2, ..., 20-N, 25) configured to integrate at least two of the frames generated by the frame generation unit into a single aggregate frame; characterized by the fact that it also comprises: a frame length control unit (20-1, 202, ..., 20-N, 25) to perform filling in the aggregate frame if the length of the aggregate frame is shorter than the length of another frame that is multiplexed at the same time; and a communication unit (21-1, 21-2, ..., 21-N) configured to transmit the frames at the same time in a multiplexed manner. 2. Communication device according to claim 1, characterized by the fact that: the frame length control unit (20-1, 20-2, ..., 20-N, 25) is configured to adjust the lengths of a plurality of multiplexed frames at the same time so that the lengths are finally made the same. 3. Communication device according to claim 2, characterized by the fact that the frame integration processing unit (20-1, 20-2, ..., 20-N, 25) is configured to integrate at least two frames having short lengths in a single frame having a long length. 4. Communication device according to claim 3, characterized by the fact that the communication unit (21-1, 21-2, ..., 20-N) includes a plurality of antenna elements capable of functioning as a adaptive matrix antenna assigning weights to the antenna elements, and the communication unit (21-1, 21-2, ..., 20-N) is capable of transmitting the plurality of frames at the same time in a multiplexed manner, and that if the frame lengths are not the same, the frame length control unit (20-1, 20-2, ..., 20-N, 25) determines which communication devices among the communication devices defined as frame destinations can be combined based on the weights of the antennas and adjusts the frame lengths by integrating the frames intended for communication devices into the combination using the frame integration processing unit. 5. Communication device according to claim 4, characterized in that if the frame length control unit is finally unable to make the frame lengths the same through frame integration, the frame length control unit frame (20-1, 20-2, ..., 20-N, 25) appropriately fills the frame having a short length so that the frames finally have the same length. 6. Communication method that comprises: a stage of frame generation to generate a plurality of frames to be transmitted at the same time; a frame integration processing step to integrate at least two of the frames generated in the frame generation step into a single aggregate frame; characterized by the fact that it also comprises: a step to perform filling in the aggregate frame if the length of the aggregate frame is shorter than the length of another frame that is multiplexed at the same time; and a communication step to transmit the plurality of frames at the same time in a multiplexed manner. 7. Computer-readable storage medium, characterized by the fact that it contains stored instructions, which, when executed by a computer, cause the computer to perform the method as defined in claim 6. 8. Communication system, characterized by the fact that it comprises: a first communication device as defined in claim 1; and a plurality of second communication devices configured to receive the multiplexed frames at the same time and transmitted from the first communication device.

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